This work is aimed at providing an understanding of the catalytic and regulatory mechanisms of the enzyme carbamyl phosphate synthetase (CPSase) from Escherichia coli. The work during the coming year will include 1) study of the binding of the allosteric effectors ornithine and UMP to CPSase by an equilibrium and dialysis procedure and the effect of substrates and analogs on this binding, 2) kinetic studies of the partial reactions catalyzed by CPSase, including initial velocity and analog inhibition (Beta, gamma-methylene ATP and phosphonate analogs of carbonate phosphate anhydride and carbamyl phosphate), and 3) implementation of the use of affinity chromatography for purification of CPSase.